Speaker

ABSTRACT

There is provided a speaker, in which a space surrounded by the drive cone, the diaphragm, and the frame is sealed, to prevent the sound quality from changing, and prevent an edge unit from being broken in particular with a large sound volume. 
     A speaker  1  includes: a frame  4;  a magnetic circuit  2;  and a vibrating unit  3.  The magnetic circuit  2  is attached to the frame  4.  The vibrating unit  3  is received in the frame  4,  and includes a drive cone  14  and a diaphragm  15  vibrated by the magnetic circuit  2.  A space surrounded by the drive cone  14,  the diaphragm  15  and the frame  4  is sealed. An edge unit  17  is attached to an outer edge of the drive cone  14.  The edge unit  17  is in an arc sectional shape, and integrally includes two roll parts  47  arranged coaxially to each other.

TECHNICAL FIELD

This invention relates to a speaker for generating sound by, forexample, vibrating a diaphragm with a supply of voice currents.

BACKGROUND ART

Conventionally various speakers (for example, Patent Document 1) aremounted on a vehicle as a moving object. The speaker disclosed in PatentDocument 1 includes: a cylindrical frame having a base plate; avibrating unit received in the frame; and a magnetic circuit unitattached to the frame, and generating sound by vibrating the vibratingunit.

The frame of the speaker has a substantially cylindrical shape forattaching to a door of a vehicle. An attaching part having a specificopening is formed on the door to which the speaker is attached. It isdifficult to freely change the size of the opening. Further, a receivingpart for attaching the frame to the attaching part is formed on theframe. An inner diameter of the receiving part is substantially the sameas an outer diameter of the attaching part.

Incidentally, if a projection projected outward is formed on a side wallof the frame, and an outer diameter of the projection is larger than theinner diameter of the receiving part, when the speaker is inserted intothe attaching part, the attaching part contacts the projection so thatthe speaker cannot be attached to the door. Accordingly, an outerdiameter of the frame of the speaker is formed in a substantiallycylindrical shape such that the outer diameter is reduced as thereceiving part extends from an inner periphery to a bottom.

The vibrating unit is received in the frame. The vibrating unitincludes: a voice coil to which voice currents are supplied; a drivecone attached to the voice coil; a diaphragm; and two edge units. Thecenter axes of the drive cone and the diaphragm are aligned (hereafterreferred to as coaxial), and an outer diameter of the diaphragm isformed large. The diaphragm is arranged on a sound emission siderelative to the drive cone.

For a purpose that the outer diameters of the diaphragm and the drivecone are substantially the same, the projection projected outward may beformed on the side wall of the frame, and the outer periphery of thedrive cone may be attached to the projection. However, as abovedescribed, because there is a problem that the projection contacts theattaching part, the outer diameter of the diaphragm is formed largerthan that of the drive cone.

Each of the two edge units is made of resin, and has an annular section.One of the two edge units is attached to an outer periphery of thediaphragm and the frame, and the other edge unit is attached to an outerperiphery of the drive cone and the frame. The edge units allow thedrive cone and the diaphragm to move in a vibration direction of thevoice coil.

Further, a sectional shape of the one edge unit is formed in an arcshape projecting toward a sound emission direction, and a sectionalshape of the other edge unit is formed in an arc shape projecting in areverse direction of the sound emission direction. Further, because theouter diameter of the diaphragm is larger than that of the drive cone,inner and outer diameter of the one edge unit is larger than that of theother edge unit.

The magnetic circuit unit includes a permanent magnet, and the voicecoil is disposed in a magnetic gap of the magnetic circuit.

In the speaker having the above described configuration, by supplyingvoice currents to the voice coil, electromagnetic force (Lorentz force)acts on the voice coil to vibrate the diaphragm and to generate soundcorresponding to the voice currents in the sound emission direction.

Further, the speaker described above is a so-called air suspensionspeaker aiming for an improvement of reproduced sound quality and for alonger operating life by sealing a space surrounded by the drive cone,the diaphragm, the two edge units, and the frame.

[Patent Document 1] Japanese Published Patent Application No.2005-191746

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

In the speaker disclosed in the Patent Document 1, when the voicecurrents are supplied to the voice coil, the drive cone transmits thevibration of the voice coil to the diaphragm, so that the diaphragmvibrates to generate sound. At this time, because the outer diameters ofthe drive cone and the diaphragm are different from each other, and theinner and outer diameters of the two edge units are different from eachother, when the diaphragm vibrates, the other edge unit attached to thedrive corn may be extended out before the one edge unit attached to thediaphragm is extended out. In this case, when the sound is reproducedwith a large volume, the sound quality of the sound may be changed.

Further, when the other edge unit is extended out, folds are formedradially. When repeating the vibration of the diaphragm, the folds maychange to cracks to break the edge unit.

The present invention aims for solving these problems. The object of thepresent invention is to provide a speaker, in which a space surroundedby a magnetic circuit unit, a diaphragm, and a frame is sealed, forpreventing a change of the sound quality and for preventing an edge unitfrom being broken in particular with a large sound volume.

Means for Solving Problem

For attaining the object, according to claim 1 of the present invention,there is provided a speaker comprising:

-   -   a frame;    -   a magnetic circuit attached to the frame;    -   a diaphragm;    -   a voice coil to which voice currents are supplied; and    -   a drive cone for transmitting a vibration of the voice coil to        the diaphragm,    -   wherein a space surrounded by the frame, the drive cone, and the        diaphragm is sealed, and    -   wherein an edge unit connected to the drive cone has an arc        shaped section, and includes a plurality of roll parts arranged        in a radial direction.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A sectional view showing a speaker according to an embodiment ofthe present invention.

FIG. 2 A sectional view showing a main part of an edge unit of thespeaker shown in FIG. 1.

FIG. 3 An explanatory view showing a difference of the lowest resonancefrequency between the present invention and a comparison example.

FIG. 4 An explanatory view showing a difference of resonance sharpnessbetween the present invention and the comparison example.

FIG. 5 A sectional view showing a main part of another embodiment of theedge unit shown in FIG. 2.

FIG. 6 A sectional view showing a main part of another embodiment of theedge unit shown in FIG. 2.

EXPLANATIONS OF LETTERS OR NUMERALS

-   1 speaker-   2 magnetic circuit unit-   3 vibrating unit-   4 frame-   12 voice coil-   14 drive cone-   15 diaphragm-   17 edge unit (edge unit connected to the drive cone)-   18 edge unit (edge unit connected to the diaphragm)-   47 roll part-   49 roll part-   K space

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, an embodiment according to the present invention will beexplained. In a speaker according to the embodiment of the presentinvention, a length (effective length) of an edge unit is extended whenthe edge unit attached not to the diaphragm but to the drive cone iscomposed of a plurality of roll parts arranged coaxially to each otherand arranged in a radial direction. Thus, in the speaker, the edge unitis prevented from extending out excessively, changing the sound quality,and being broken when repeating a vibration in particular with a largesound volume.

Further, a corrugation damper is deformed perpendicular to the centeraxis of a voice coil to prevent a vibrating unit, namely, the voicecoil, a voice coil bobbin, the diaphragm, or the like from oscillatinghorizontally (perpendicular to the center axis of the voice coil).However, in this speaker, the drive cone and the diaphragm are notlocally and largely deformed. Therefore, abnormal vibration such as seenin a rolling phenomenon to spoil sound quality and sibilating soundgenerated when the voice coil bobbin contacts a plate or a magnet arenot generated, and high quality sound or clear sound can be reproduced.

The edge unit connected to the diaphragm may have a roll part. In thiscase, a length (effective length) of the edge unit connected to thediaphragm is prevented from extending longer than needs, and adifference between the lengths of the edge units attached to thediaphragm and attached to the drive cone can be reduced.

Further, the edge unit attached to the drive cone may have two rollparts. In this case, even when a total width of the edge unit (adistance from an inner periphery to an outer periphery of the edge unit)is short, the length of the edge unit can be long enough.

Further, the inner periphery of the edge unit may be connected to anouter periphery of the diaphragm, and the outer periphery may beattached to the frame. In this case, the edge unit can surely andvibratably support the diaphragm.

Further, a curvature radius of a section of the outer roll part (nearthe frame) may be smaller than that of the inner roll part (near thevoice coil bobbin). In this case, because the rigidity of the outer rollpart is larger than that of the inner roll part, in particular when thevibration of the diaphragm is large, namely, a large sound volume isreproduced, a deformation of the outer roll part is regulated, so that adeformation such as radial folds is prevented at the outer roll part,namely, outside of the edge unit. Therefore, in particular when a largesound volume is reproduced abnormal sound is prevented from being causedby radial folds at the outer roll part, namely, outside of the edgeunit.

Further, a space surrounded by the drive cone, the diaphragm, and theframe may be a sealed space. In this case, the air in the spaceattenuates the vibration of the drive cone, so that a damper used in aconventional speaker is not needed. Therefore, a structure of thespeaker can be simplified. Embodiment

An embodiment of the present invention will be explained with referenceto FIGS. 1 to 4. A speaker 1 according to the embodiment of the presentinvention shown in FIG. 1 is mounted on a vehicle as a moving object toprovide voice information to crews in the vehicle.

As shown in FIG. 1, the speaker 1 includes: a frame 4; a magneticcircuit 2; a vibrating unit 3 for generating sound; and a wiringstructure 5.

As shown in FIG. 1, the frame 4 includes: a frame main body 20; anot-shown frame for connector; a cover for the magnetic circuit unit 22;and a gasket 23.

The frame main body 20 is made of metal such as aluminum. The frame mainbody 20 includes: an annular bottom part 24; a cylinder part 25extending upward from a periphery of the bottom part 24; and a flangepart 26 projecting from an inner wall (inner side wall, inner peripheralwall) of the cylinder part 25.

The flange part 26 is formed in an annular shape and projected toward aninside of the cylinder part 25 from the inner wall of the cylinder part25. The flange part 26 is extended in the whole circumference of thecylinder part 25 along the inner wall of the cylinder part 25. Further,a single hole 28 into which a later-described not-shown tube member ispressed is provided on the flange part 26. Of course, the hole 28penetrates the frame main body 20, namely, the flange part 26 of theframe 4.

The frame for connector is attached to the frame main body 20. Aconnector for connecting to the above-described amplifier mounted on avehicle is attached to the frame for connector. The connector may beconnected to not only the amplifier but also other electroniccomponents.

The cover for the magnetic circuit unit 22 includes an annular bottompart 30, and a cylinder part 31 extending upward from a periphery of thebottom part 30. The cover for the magnetic circuit unit 22 is fixed to alater-described yoke 7 of a magnetic circuit unit 2 with a bolt 32. Aplate 9 and the frame main body 20 are fixed with a bolt 33. When thecover for the magnetic circuit unit 22 is fixed to the frame main body20, the cover for the magnetic circuit unit 22 is made coaxial with theframe main body 20. Here, “coaxial” means that center axes of the coverfor the magnetic circuit unit 22 and the frame main body 20 aresubstantially the same.

A gasket 23 is formed in an annular shape. The gasket 23 is overlappedwith a periphery (outer circumference) of the frame main body 20, andsandwiches a later-described edge unit 18 with the periphery, and then,fixed to the frame main body 20 with such as an adhesive agent. Thegasket 23 and the periphery of the frame main body 20 sandwiches theedge unit 18 so as to fix a later-described diaphragm 15 on the framemain body 20.

The magnetic circuit unit 2 is attached to the frame 4 by means that themagnetic circuit unit 2 is fixed to both the cover for the magneticcircuit unit 22 and the frame main body 20. As shown in FIG. 1, themagnetic circuit unit 2 includes: the yoke 7 made of magnetic material(so-called paramagnetic material or ferromagnetic material); a magnet 8;and the plate made of magnetic material (so-called paramagnetic materialor ferromagnetic material). The yoke 7 is an external magnet typemagnetic circuit integrally including: an annular bottom plate 10; and acylindrical center pole 11 extending from an inner edge locatingcentrally in the bottom plate 10. In this embodiment, the externalmagnet type magnetic circuit is disclosed. However, according to thepresent invention, an internal magnet type magnetic circuit or amagnetic circuit using both the internal magnet and the external magnet(magnetic circuit having magnets both inside and outside of the voicecoil bobbin) can be used. Further, according to this embodiment, anopening communicating with an outside of the speaker is provided on thecenter pole 11. However, according to the present invention, it isacceptable that the opening may not be provided.

The magnet 8 is formed in an annular shape. An inner diameter of themagnet 8 is larger than an outer diameter of the center pole 11. Themagnet 8 is overlapped with the bottom plate 10 while the center pole 11is disposed in an inside of the magnet 8. The above-described magnet 8may be a magnet excited by a permanent magnet or by a DC power source.

The plate 9 is formed in an annular shape. An inner diameter of theplate 9 is larger than the outer diameter of the center pole 11. Theplate 9 is overlapped with the magnet 8 while the center pole 11 of theyoke 7 and a later-described voice coil bobbin 13 are disposed in aninside of the plate 9. The yoke 7, the magnet 8, and the plate 9 arearranged coaxially to each other, namely, the center axes thereof arearranged substantially the same. Therefore, inner circumferential wallsof the magnet 8 and the plate 9 are separated from an outercircumferential wall of the center pole 11 of the yoke 7.

Further, the above-described yoke 7 is fixed on the cover for themagnetic circuit unit 22 with the bolt 32 penetrating the cylindricalbottom part 30 and the bottom plate 10. Further, the bolt 33 penetratingthe bottom part 24 of the frame main body 20 is screwed into the plate 9to fix the plate 9 to the frame main body 20. Thus, the magnetic circuitunit 2 is fixed to the frame 4 by means that the plate 9 is fixed to theframe main body 20, and the bottom plate 10 is fixed on the cover forthe magnetic circuit unit 22. Of course, the yoke 7, the magnet 8, andthe plate 9 are arranged coaxially with the frame 4.

According to the above-described structure, in the magnetic circuit unit2, a magnetic gap G having a large magnetic flux density is formedbetween the outer peripheral wall of the center pole 11 of the yoke 7and the inner peripheral wall of the plate 9. Namely, in the magneticgap G, the magnetic circuit unit 2 makes the electromagnetic force(Lorentz force) acting on a voice coil 12 to vibrate the diaphragm 15.

The vibrating unit 3 is received in the frame main body 20 of the frame4. The vibrating unit 3 includes the voice coil 12, the voice coilbobbin 13, a drive cone 14, the diaphragm 15, and a center cap 16.Namely, the vibrating unit 3 includes the drive cone 14 and thediaphragm 15. In this embodiment, two voice coils are provided, and twovoice coil bobbins 13 are wound integrally (not shown). Further, beforethe diaphragm 15 is vibrated, the voice coils are arranged coaxially toeach other, and disposed in the above-described magnetic gap G of themagnetic circuit unit 2. Voice currents are supplied to the voice coil12.

The voice coil bobbin 13 is formed in a cylinder shape. An innerdiameter of the voice coil bobbin 13 is larger than the outer diameterof the center pole 11 of the yoke 7. An outer diameter of the voice coilbobbin 13 is smaller than the inner diameters of the plate 9 and themagnet 8. The voice coil bobbin 13 is arranged coaxially with the yoke7, the plate 9, and the voice coil 12. One end of the voice coil bobbin13 is inserted into the magnetic gap G, and the voice coil 12 isattached to the periphery of the one end of the voice coil bobbin 13.The voice coil bobbin 13 is movably supported along the center axis ofthe yoke 7 by the drive cone 14 and the diaphragm 15. The center axes ofthe yoke 7 and the voice coil bobbin 13 are substantially the same asthat of the speaker 1.

The drive cone 14 transmits the vibration of the voice coil 12 to thelater-described diaphragm 15. The drive cone 14 is made of resin or thelike. The drive cone 14 is formed in an annular shape, and an inner edgethereof is attached to an outer wall of the other end of the voice coilbobbin 13 in the center axis direction. Therefore, the drive cone 14 isattached to the voice coil 12 via the voice coil bobbin 13.

An inner edge of a thin plate shaped edge unit 17 is attached(connected) to an outer edge of the drive cone 14 with the adhesiveagent or the like. The edge unit 17 is made of such as rubber or resin(namely, elastic material). The edge unit 17 is formed in an annularshape surrounding the drive cone 14. As shown in FIG. 2, the edge unit17 integrally includes a plurality of roll parts 47 and a flange formedat an outer edge thereof.

In FIG. 2, two roll parts are provided. Each roll part 47 is formed inan annular shape to surround the drive cone 14, and a sectional shape ofthe roll part 47 is in a thin-plate and an arc. Curvature radii of thesections of the two roll parts 47 are substantially the same. The tworoll parts 47 are arranged coaxially to each other, and in a radialdirection of the edge unit 17, namely, the speaker 1. Namely, one rollpart 47 is arranged at an inside of the other roll part 47. Further, anouter edge of the one roll part 47 is continued to an inner edge of theother roll part 47. A planar shape of the flange 48 is an annular shape,and a sectional shape of the flange 48 is a plane shape. The roll parts47 are arranged in an inside of the flange 48, and an inner edge of theflange 48 is continued to an outer edge of the above-described otherroll part 47. Namely, the flange 48 is projected outward from the otherroll part 47. The flange 48 is coaxial to the two roll parts 47.

In the edge unit having the above-described structure, the flange 48(namely, the outer edge) is sandwiched between a flange part 26 of theframe main body 20 and a later-described positioning member 34 of thewiring structure 5, and fixed to them. Namely, the drive cone 14 isattached to the frame main body 20, namely, the frame 4 via the edgeunit 17. Further, the elastically deformable edge unit 17 attaches thedrive cone 14 to the frame 4 movably in the center axis direction.Further, in this embodiment, the edge unit 17 is attached to the frame4, and both sections of the two roll parts 47 are projected with arcshapes in a direction opposite to the sound emission direction.

The diaphragm 15 is made of resin or the like. The diaphragm 15 isformed in an annular shape. An inner diameter of the diaphragm 15 islarger than an inner diameter of the drive cone 14, and an outerdiameter of the diaphragm 15 is larger than an outer diameter of thedrive cone 14. The diaphragm 15 is fixed on a part of the drive cone 14,in particular, grooves thereof indicated by reference numbers 50, 51, 52in FIG. 1 with the adhesive agent or the like.

Further, the diaphragm 15 is arranged coaxially to the drive cone 14.The thin plate shaped edge unit 18 having a semi-circular section isattached to the outer edge of the diaphragm 15 with the adhesive agentor the like. The edge unit 18 includes a single roll part 49 of whichsection is in an arc shape projected in the sound emission direction.The edge unit 18 is made of rubber or resin (namely, the elasticmaterial). An outer edge of the edge unit 18 is sandwiched between anouter edge of the cylinder part 25 of the frame main body 20 and thegasket 23, and thus, the edge unit 18 is fixed to these. Namely, thediaphragm 15 is attached to the frame main body 20, namely, the frame 4via the edge unit 18. Further, the elastically deformable edge unit 18attaches the diaphragm 15 to the frame 4 movably in the center axisdirection of the speaker 1. Thus, the speaker 1 includes a plurality ofedge units (two in FIG. 1).

The center cap 16 is made of resin or the like. The center cap 16 is ina circular shape. A sectional shape of the center cap 16 is a convexshape in the center thereof in a sound emission direction, and a concaveshape from the center toward an outer edge thereof. An outer diameter ofthe center cap 16 is larger than the inner diameter of the diaphragm 15,and is smaller than the outer diameter of the diaphragm 15. An outeredge of the center cap 16 is overlapped with the diaphragm 15, andattached to the diaphragm 15 along a whole periphery with the adhesiveagent or the like.

The above-described drive cone 14, the diaphragm 15, and the center cap16 of the vibrating unit 3 are, of course, arranged coaxially to theframe 4 and the magnetic circuit unit 2. In the vibrating unit 3, whenthe voice currents corresponding to voice data is supplied to the voicecoil 12, the drive cone 14 transmits the vibration of the voice coil 12to the diaphragm 15, and the diaphragm 15 vibrates along theabove-described center axis to generate sound corresponding to the voicecurrents.

Further, a space K surrounded by the above-described drive cone 14, thediaphragm 15, the edge units 17, 18, and an inner wall of the frame 4 ofthe frame main body 20 is sealed. Namely, the space K surrounded by thedrive cone 14, the diaphragm 15, the edge units 17, 18, and the innerwalls of the frame 4 of the frame main body 20 is hermetically-closed.

Therefore, when the voice coil bobbin 13 of the above-describedvibrating unit 3 vibrates with the voice coil 12, and the vibration ofthe voice coil 12 is transmitted to the drive cone 14 and the diaphragm15. Then, because an air in the space K between the drive cone 14 andthe diaphragm 15 is repeatedly compressed and expanded due todisplacement of the drive cone 14 and the diaphragm 15 and displacementof the edge units 17, 18, an air spring is developed.

In this embodiment, when an effective area of the diaphragm 15 is S1, aneffective area of the drive cone 14 is S2, the difference S is expressedby S=S1−S2. Further, when a volume of the air in the sealed space Kbetween the drive cone 14 and the diaphragm 15 is V, a stiffnessconstant indicating the spring characteristic of the air spring isproportional to S/V. Namely, in this embodiment, the springcharacteristic as the air spring occurs based on the air in the sealedspace K between the drive cone 14 and the diaphragm 15 allows toregulate an abnormal behavior such that the diaphragm 15 vibrates invery large amplitude, to reproduce an acoustic characteristic of thespeaker 1 for a long time, and to maintain reliability of the speaker 1even when the diaphragm 15 vibrates in large amplitude for a long time.

As shown in FIG. 1, the wiring structure 5 includes: the positioningmember 34; a plurality of not-shown tinsel wires; a plurality ofnot-shown lead wires; and a tube member. The positioning member 34 isformed in an annular shape, and an outer diameter of the positioningmember 34 is equal to an inner diameter of the cylinder part 25 of theframe main body 20.

The positioning member 34 and the flange part 26 sandwich the flange 48,and the positioning member 34 is fixed on the flange part 26, namely,the frame main body 20 with a not-shown bolt, the adhesive agent, or thelike. One end of the tinsel wire is connected to the voice coil 12, andthe other end is attached to a terminal of the positioning member 34.The lead wire is a so-called covered wire having a conductive core wireand an insulating cover. One end of the lead wire is attached to theterminal of the positioning member 34, and the other end is attached toa terminal of a connector of a connector frame, and connected to thevoice coil 12 via the tinsel wire.

The tube member is made of rubber, and formed in a tubular shape. Thetube member may be made of resin or the like other than rubber. The tubemember is so shaped that the rubber surrounds each of four lead wires byinsert molding. The lead wires are inserted into an inside of the tubemember 38, and the tube member is pressed into a hole of the frame mainbody 20, and guides the lead wires to an outside of the space K When thedrive cone 14 and the diaphragm 15 vibrate, the tube member keeps thespace K sealed so that the air in the space K may not leak. Further, asdescribed the above, it is preferable that the tube member is made ofelastic rubber for keeping the space K sealed.

The above-described wiring structure 5 is assembled by attaching thetinsel wires and the lead wires to the terminal, by pressing the tubemember into which all of the lead wires are inserted into the hole, andby attaching the lead wires to the terminal of the connector. Then, byconnecting sequentially the lead wires, the tinsel wires, and the voicecoil 12 in series, the wiring structure 5 supplies the voice currentsfrom the terminal of the connector to the voice coil 12.

According to the speaker 1 having the above-described structure, thevoice currents are supplied to the voice coil 12 via the lead wires inthe wiring structure 5, and the voice coil 12 disposed in the magneticgap G vibrates along the center axis corresponding to the voicecurrents. Then, the voice coil bobbin 13 around the periphery of thevoice coil 12 is wound, the drive cone 14, and the diaphragm 15 vibratesalong the center axis of the speaker 1. Namely, the vibration of thevoice coil 12 is transmitted to the diaphragm 15 via the drive cone 14,and the diaphragm 15 vibrates to generate sound corresponding to thevoice currents.

According to this embodiment, because the edge unit 17 connected to thedrive 14 cone, of which outer diameter is smaller than that of thediaphragm 15, is composed of a plurality of roll parts 47 coaxially toeach other and arranged in a radial direction, a length (effectivelength) of the section of the edge unit 17 becomes large. Therefore, thespeaker 1 prevents the edge unit 17 from extending out excessively, andin particular, prevents the edge unit 17 from being broken whenrepeating the change of the sound quality and the vibration of thereproduced sound with a large volume.

The edge unit 18 connected to the diaphragm 15 includes a single rollpart 49. Therefore, the length (effective length) of the edge unit 18connected to the diaphragm 15 is prevented from being larger thannecessary, and a difference between the length of the edge unit 18 andthe length of the edge unit 17 attached to the drive cone 14 isregulated.

Further, the corrugation damper is deformed perpendicular to the centeraxis of the voice coil 12 to prevent the vibrating unit, namely, thevoice coil 12, the voice coil bobbin 13, the diaphragm 15, or the likefrom oscillating horizontally (perpendicular to the center axis of thevoice coil 12). However, in this speaker 1, the drive cone 14 and thediaphragm 15 are not locally and largely deformed. Therefore, abnormalvibration such as seen in a rolling phenomenon to spoil sound qualityand sibilating sound generated when the voice coil bobbin 13 contactsthe plate 9 or the magnet 8 are not generated, and high quality clearsound can be reproduced.

Further, the edge unit 17 attached to the drive cone 14 includes tworoll parts 47. In this case, even a whole width (a distance from aninner edge to an outer edge) of the edge unit 17 is small, the enoughlength of the edge unit 17 in the cross-section can be provided.

Further, an inner edge of the edge unit 18 is connected to an outer edgeof the diaphragm 15, and an outer edge of the edge unit 18 is attachedto the frame 4. Therefore, the edge unit 18 surely supports movably thediaphragm 15.

Next, inventors of the present invention have confirmed an effect of thespeaker 1 according to the above-described embodiment. Results are shownin FIGS. 3 and 4. Comparison examples shown by the dotted lines in FIGS.3 and 4 correspond to a speaker using an edge unit having the singleroll part disclosed in the Patent Document 1. Present inventions shownby the solid lines in FIGS. 3 and 4 correspond to the speaker 1 usingthe edge unit 17 having the two roll parts 47 similar to theabove-described embodiment.

FIG. 3 shows a change of a lowest resonance frequency (f0) when applyingpower of 1 W to 32 W to the voice coils of the speakers of the presentinvention and the comparison example. The horizontal axis indicates thepower, and the vertical axis indicates a change rate of the lowestresonance frequency. FIG. 4 shows a change of a quality factor (Q0) whenapplying power of 1 W to 32 W to the voice coils of the speakers of thepresent invention and the comparison example. The horizontal axisindicates the power, and the vertical axis indicates a change rate ofthe quality factor.

According to FIGS. 3 and 4, it is clear that the both change rate of thelowest resonance frequency (f0) and the quality factor (Q0) of thepresent invention are smaller than those of the comparison example.Namely, a change of the sound quality of the present invention issmaller than that of the comparison example.

Further, in the speaker 1, the air spring, which the air in the sealedspace K between the drive cone 14 and the diaphragm 15 develops, absorbsvibrating energy of the voice coil bobbin 13, the drive cone 14, and thediaphragm 15 to attenuate the vibration of the drive cone 14, thediaphragm 15, and the voice coil bobbin 13. Therefore, it is unnecessaryto provide a damper as the conventional speaker includes. Namely, in thespeaker 1 according to this embodiment, the drive cone 14 and thediaphragm 15 themselves work as the damper to attenuate the vibration ofthe drive cone 14, the diaphragm 15, and the voice coil bobbin 13.Therefore, it is unnecessary to equip the damper for supporting thevoice coil bobbin 13 at a back side of the drive cone 14 and thediaphragm 15. Therefore. a size of the speaker 1 in the direction of thespeaker 1 can be reduced by omitting the damper and a space forinstalling the damper, and a slim speaker 1 required by an audio systemmounted on a vehicle can be realized.

Further, the drive cone 14 is disposed coaxially at a back side of thediaphragm 15 for realizing the sealed space K between the drive cone 14and the diaphragm 15. This drive cone 14 may be made of the samematerial as the diaphragm 15. When comparing with a conventionalcorrugation damper, mechanical fatigue is less likely to occur.Therefore, reliability reduction of the speaker 1 caused by themechanical fatigue of the components is prevented, and the life time ofthe speaker 1 can be increased.

Further, the corrugation damper is deformed perpendicular to the centeraxis of the voice coil to prevent the vibrating unit, namely, the voicecoil, the voice coil bobbin, the diaphragm, or the like from oscillatinghorizontally (perpendicular to the center axis of the voice coil).However, in this speaker 1, the drive cone 14 and the diaphragm 15 arenot locally and largely deformed. Therefore, abnormal vibration such asseen in a rolling phenomenon to spoil sound quality and sibilating soundgenerated when the voice coil bobbin 13 contacts the plate 9 or themagnet 8 are not generated, and high quality clear sound can bereproduced.

In the speaker 1 according to this embodiment, when the diaphragm 15vibrates, the air in the sealed space K between the drive cone 14 andthe diaphragm 15 is repeatedly compressed and expanded. Therefore, theedge units 17, 18 of the drive cone 14 and the diaphragm 15 are lesslikely to be deformed due to air pressure (back pressure) received atthe back side. Therefore, without generating the abnormal vibration orthe sibilating sound, the drive cone 14 and the diaphragm 15 can vibratewith large amplitude, and loud sound can be reproduced. Further, owingto the drive cone 14 and the edge unit 17, it becomes possible that theair spring developed by the air in the space K prevents abnormalbehavior of the diaphragm 15 vibrating with very large amplitude, thatthe acoustic characteristic of the speaker 1 is reproduced continuously,that the acoustic characteristic of the speaker 1 is reproduced for along time, and that reliability of the speaker 1 is maintained even whenthe diaphragm 15 vibrates with large amplitude for a long time.

In the above-described embodiment, two roll parts 47 compose the edgeunit 47 supporting the drive cone 14. However, according to the presentinvention, three roll parts 47 may compose the edge unit 47. In short,according to the present invention, the edge unit 47 connected to thedrive cone 14 needs is to include a plurality of roll parts 47. Further,according to the present invention, preferably, the edge unit 48connected to the diaphragm 15 includes a single roll part 49.

Further, according to the above-described embodiment, all the roll parts47 project in the direction opposite to the sound emission direction.However, according to the present invention, as shown in FIG. 6, theroll part 47 may projects in the sound emission direction. Incidentally,in FIG. 6, an outer roll part 47 projects in the sound emissiondirection, and an inner roll part 47 projects in the direction oppositeto the sound emission direction. In short, according to the presentinvention, each roll part 47 may project in the sound emissiondirection, and may project in the direction opposite to the soundemission direction.

Further, according to the above-described embodiment, the curvatureradii of the sections of all the roll parts 47 are substantially thesame. However, according to the present invention, as shown in FIG. 5,the curvature radius of the section of the outer roll part 47 may besmaller than that of the inner roll part 47. In this case, becauserigidity of the outer roll part 47 is larger than that of the inner rollpart 47, when the amplitude of the diaphragm 15 is large, namely, whenthe large sound volume is generated, deformation of the outer roll part47 is regulated and the deformation such as radial folds on the outerroll part 47 is prevented from generating, namely, the edge unit 17 frombeing deformed such as radial folds. Therefore, in particular, when alarge sound volume is generated, the deformation such as radial folds onthe outer roll part 47, namely, the edge unit 17 is prevented, andabnormal sound is prevented from generating because of a crack on theedge unit, and the edge unit 17 is prevented from being broken.According to the present invention, more than two roll parts 47 can beprovided, in short, it is preferable that the curvature radius of thesection of the outermost roll part 47 be smaller than that of theinnermost roll part 47.

According to the above-described embodiment, the speaker 1 describedbelow is obtained.

(Note) a speaker 1 comprising:

-   -   a frame 4;    -   a magnetic circuit 2 attached to the frame 4;    -   a diaphragm 15;    -   a voice coil 12 to which voice currents are supplied; and    -   a drive cone 14 for transmitting a vibration of the voice coil        12 to the diaphragm 15,    -   wherein an edge unit 17 connected to the drive cone 14 has an        arc shaped section, and includes a plurality of roll parts 47        arranged in a radial direction.

According to the Note, because the edge unit 17 attached to the drivecone 14 includes a plurality of roll parts 47 arranged in the radialdirection, the length of the section of the edge unit 17 becomes large.Therefore, in the speaker 1, the edge unit 17 is prevented fromextending out excessively, and in particular, a change of a soundquality with a large sound volume, and breaking of the edge unit 17 whenrepeating a vibration are prevented.

Although the present invention has been fully described by way ofexample with reference to the accompanying drawings, it is to beunderstood that various changes and modifications will be apparent tothose skilled in the art. Therefore, unless otherwise such changes andmodifications depart from the scope of the present invention hereinafterdefined, they should be construed as being included therein.

1. A speaker comprising: a frame; a magnetic circuit attached to theframe; and a vibrating unit having a diaphragm, a voice coil to whichvoice currents are supplied, a drive cone for transmitting a vibrationof the voice coil to the diaphragm, and first and second edge units,wherein the diaphragm is supported by the frame with the first edgeunit, wherein the drive cone is supported by the frame with the secondedge unit, and wherein the second edge unit is formed in an arc shapedsection, and includes a plurality of roll parts arranged in a radialdirection.
 2. The speaker as claimed in claim 1, wherein the second edgeunit is disposed lower than the first edge unit.
 3. The speaker 1 asclaimed in claim 2, wherein an outer edge of the drive cone is disposedlower than a connection between the diaphragm and the first edge unit,and extends near the connection in a direction from the voice coil tothe frame.
 4. The speaker as claimed in claim 3, wherein the roll partsof the second edge unit are disposed lower than an outer periphery ofthe drive cone.
 5. The speaker as claimed in claim 4, wherein the secondedge unit includes a first roll part projected in a sound emissiondirection, and a second roll part projected in a direction opposite tothe sound emission direction, and wherein the second edge unit includesa plurality of second roll parts sandwiching the first roll part.
 6. Thespeaker as claimed in claim 5, wherein a tip of the first roll part isdisposed lower than the outer edge of the drive cone, and wherein a tipof the second roll part is disposed lower than the tip of the first rollpart.
 7. The speaker as claimed in claim 6, wherein the tip of the firstroll part is disposed on an outer periphery than the central positionbetween the tips of the second roll parts.
 8. The speaker as claimed inclaim 6, wherein a curvature radius of a section of the second roll partdisposed outermost in a plurality of second roll parts is smaller thanthat of the second roll part disposed innermost in the other second rollparts.
 9. The speaker as claimed in claim 4, wherein the second edgeunit includes a first roll part projected in a sound emission directionand a second roll part projected in a direction opposite to the soundemission direction, and wherein the first and the second roll parts areadjacent to each other.
 10. The speaker as claimed in claim 6, wherein apart between an inner edge and an outer edge of the drive cone isconnected to a part between an inner edge and an outer edge of thediaphragm.
 11. The speaker as claimed in claim 10, wherein the partbetween the inner edge and the outer edge of the drive cone is directlyconnected to the inner edge of the diaphragm.
 12. The speaker as claimedin claim 1, wherein a part between an inner edge and an outer edge ofthe drive cone supports the diaphragm.
 13. The speaker as claimed inclaim 1, wherein the vibrating unit includes a center cap, and whereinan outer edge of the center cap is supported by the diaphragm.
 14. Thespeaker as claimed in claim 13, wherein a part between an inner edge andan outer edge of the diaphragm supports the center cap, and wherein theinner edge of the diaphragm is supported by the drive cone.
 15. Thespeaker as claimed in claim 11, wherein a plurality of the edge unitshave air tightness, and wherein a space surrounded by the frame and thevibrating unit is sealed.